requireContext => requireContext.keys().map(requireContext) 的解释
参考资料:
https://www.cnblogs.com/onesea/p/15346649.html
https://blog.csdn.net/weixin_34188576/article/details/113316033
https://www.csdn.net/tags/OtDaUg0sODE1MDMtYmxvZwO0O0OO0O0O.html
https://z.itpub.net/article/detail/36631E90CB1916FBCB1C1B282E895950
https://blog.csdn.net/weixin_34112030/article/details/91420897